diff.con commit git-send-pack: documentation (9553d20)
   1/*
   2 * Copyright (C) 2005 Junio C Hamano
   3 */
   4#include <sys/types.h>
   5#include <sys/wait.h>
   6#include <signal.h>
   7#include "cache.h"
   8#include "quote.h"
   9#include "diff.h"
  10#include "diffcore.h"
  11
  12static const char *diff_opts = "-pu";
  13static unsigned char null_sha1[20] = { 0, };
  14
  15static int reverse_diff;
  16static int use_size_cache;
  17
  18static const char *external_diff(void)
  19{
  20        static const char *external_diff_cmd = NULL;
  21        static int done_preparing = 0;
  22
  23        if (done_preparing)
  24                return external_diff_cmd;
  25
  26        /*
  27         * Default values above are meant to match the
  28         * Linux kernel development style.  Examples of
  29         * alternative styles you can specify via environment
  30         * variables are:
  31         *
  32         * GIT_DIFF_OPTS="-c";
  33         */
  34        if (gitenv("GIT_EXTERNAL_DIFF"))
  35                external_diff_cmd = gitenv("GIT_EXTERNAL_DIFF");
  36
  37        /* In case external diff fails... */
  38        diff_opts = gitenv("GIT_DIFF_OPTS") ? : diff_opts;
  39
  40        done_preparing = 1;
  41        return external_diff_cmd;
  42}
  43
  44static struct diff_tempfile {
  45        const char *name; /* filename external diff should read from */
  46        char hex[41];
  47        char mode[10];
  48        char tmp_path[50];
  49} diff_temp[2];
  50
  51static int count_lines(const char *filename)
  52{
  53        FILE *in;
  54        int count, ch, completely_empty = 1, nl_just_seen = 0;
  55        in = fopen(filename, "r");
  56        count = 0;
  57        while ((ch = fgetc(in)) != EOF)
  58                if (ch == '\n') {
  59                        count++;
  60                        nl_just_seen = 1;
  61                        completely_empty = 0;
  62                }
  63                else {
  64                        nl_just_seen = 0;
  65                        completely_empty = 0;
  66                }
  67        fclose(in);
  68        if (completely_empty)
  69                return 0;
  70        if (!nl_just_seen)
  71                count++; /* no trailing newline */
  72        return count;
  73}
  74
  75static void print_line_count(int count)
  76{
  77        switch (count) {
  78        case 0:
  79                printf("0,0");
  80                break;
  81        case 1:
  82                printf("1");
  83                break;
  84        default:
  85                printf("1,%d", count);
  86                break;
  87        }
  88}
  89
  90static void copy_file(int prefix, const char *filename)
  91{
  92        FILE *in;
  93        int ch, nl_just_seen = 1;
  94        in = fopen(filename, "r");
  95        while ((ch = fgetc(in)) != EOF) {
  96                if (nl_just_seen)
  97                        putchar(prefix);
  98                putchar(ch);
  99                if (ch == '\n')
 100                        nl_just_seen = 1;
 101                else
 102                        nl_just_seen = 0;
 103        }
 104        fclose(in);
 105        if (!nl_just_seen)
 106                printf("\n\\ No newline at end of file\n");
 107}
 108
 109static void emit_rewrite_diff(const char *name_a,
 110                              const char *name_b,
 111                              struct diff_tempfile *temp)
 112{
 113        /* Use temp[i].name as input, name_a and name_b as labels */
 114        int lc_a, lc_b;
 115        lc_a = count_lines(temp[0].name);
 116        lc_b = count_lines(temp[1].name);
 117        printf("--- %s\n+++ %s\n@@ -", name_a, name_b);
 118        print_line_count(lc_a);
 119        printf(" +");
 120        print_line_count(lc_b);
 121        printf(" @@\n");
 122        if (lc_a)
 123                copy_file('-', temp[0].name);
 124        if (lc_b)
 125                copy_file('+', temp[1].name);
 126}
 127
 128static void builtin_diff(const char *name_a,
 129                         const char *name_b,
 130                         struct diff_tempfile *temp,
 131                         const char *xfrm_msg,
 132                         int complete_rewrite)
 133{
 134        int i, next_at, cmd_size;
 135        const char *diff_cmd = "diff -L%s%s -L%s%s";
 136        const char *diff_arg  = "%s %s||:"; /* "||:" is to return 0 */
 137        const char *input_name_sq[2];
 138        const char *path0[2];
 139        const char *path1[2];
 140        const char *name_sq[2];
 141        char *cmd;
 142
 143        name_sq[0] = sq_quote(name_a);
 144        name_sq[1] = sq_quote(name_b);
 145
 146        /* diff_cmd and diff_arg have 6 %s in total which makes
 147         * the sum of these strings 12 bytes larger than required.
 148         * we use 2 spaces around diff-opts, and we need to count
 149         * terminating NUL, so we subtract 9 here.
 150         */
 151        cmd_size = (strlen(diff_cmd) + strlen(diff_opts) +
 152                        strlen(diff_arg) - 9);
 153        for (i = 0; i < 2; i++) {
 154                input_name_sq[i] = sq_quote(temp[i].name);
 155                if (!strcmp(temp[i].name, "/dev/null")) {
 156                        path0[i] = "/dev/null";
 157                        path1[i] = "";
 158                } else {
 159                        path0[i] = i ? "b/" : "a/";
 160                        path1[i] = name_sq[i];
 161                }
 162                cmd_size += (strlen(path0[i]) + strlen(path1[i]) +
 163                             strlen(input_name_sq[i]));
 164        }
 165
 166        cmd = xmalloc(cmd_size);
 167
 168        next_at = 0;
 169        next_at += snprintf(cmd+next_at, cmd_size-next_at,
 170                            diff_cmd,
 171                            path0[0], path1[0], path0[1], path1[1]);
 172        next_at += snprintf(cmd+next_at, cmd_size-next_at,
 173                            " %s ", diff_opts);
 174        next_at += snprintf(cmd+next_at, cmd_size-next_at,
 175                            diff_arg, input_name_sq[0], input_name_sq[1]);
 176
 177        printf("diff --git a/%s b/%s\n", name_a, name_b);
 178        if (!path1[0][0]) {
 179                printf("new file mode %s\n", temp[1].mode);
 180                if (xfrm_msg && xfrm_msg[0])
 181                        puts(xfrm_msg);
 182        }
 183        else if (!path1[1][0]) {
 184                printf("deleted file mode %s\n", temp[0].mode);
 185                if (xfrm_msg && xfrm_msg[0])
 186                        puts(xfrm_msg);
 187        }
 188        else {
 189                if (strcmp(temp[0].mode, temp[1].mode)) {
 190                        printf("old mode %s\n", temp[0].mode);
 191                        printf("new mode %s\n", temp[1].mode);
 192                }
 193                if (xfrm_msg && xfrm_msg[0])
 194                        puts(xfrm_msg);
 195                if (strncmp(temp[0].mode, temp[1].mode, 3))
 196                        /* we do not run diff between different kind
 197                         * of objects.
 198                         */
 199                        exit(0);
 200                if (complete_rewrite) {
 201                        fflush(NULL);
 202                        emit_rewrite_diff(name_a, name_b, temp);
 203                        exit(0);
 204                }
 205        }
 206        fflush(NULL);
 207        execlp("/bin/sh","sh", "-c", cmd, NULL);
 208}
 209
 210struct diff_filespec *alloc_filespec(const char *path)
 211{
 212        int namelen = strlen(path);
 213        struct diff_filespec *spec = xmalloc(sizeof(*spec) + namelen + 1);
 214        spec->path = (char *)(spec + 1);
 215        strcpy(spec->path, path);
 216        spec->should_free = spec->should_munmap = 0;
 217        spec->xfrm_flags = 0;
 218        spec->size = 0;
 219        spec->data = NULL;
 220        spec->mode = 0;
 221        memset(spec->sha1, 0, 20);
 222        return spec;
 223}
 224
 225void fill_filespec(struct diff_filespec *spec, const unsigned char *sha1,
 226                   unsigned short mode)
 227{
 228        if (mode) {
 229                spec->mode = DIFF_FILE_CANON_MODE(mode);
 230                memcpy(spec->sha1, sha1, 20);
 231                spec->sha1_valid = !!memcmp(sha1, null_sha1, 20);
 232        }
 233}
 234
 235/*
 236 * Given a name and sha1 pair, if the dircache tells us the file in
 237 * the work tree has that object contents, return true, so that
 238 * prepare_temp_file() does not have to inflate and extract.
 239 */
 240static int work_tree_matches(const char *name, const unsigned char *sha1)
 241{
 242        struct cache_entry *ce;
 243        struct stat st;
 244        int pos, len;
 245
 246        /* We do not read the cache ourselves here, because the
 247         * benchmark with my previous version that always reads cache
 248         * shows that it makes things worse for diff-tree comparing
 249         * two linux-2.6 kernel trees in an already checked out work
 250         * tree.  This is because most diff-tree comparisons deal with
 251         * only a small number of files, while reading the cache is
 252         * expensive for a large project, and its cost outweighs the
 253         * savings we get by not inflating the object to a temporary
 254         * file.  Practically, this code only helps when we are used
 255         * by diff-cache --cached, which does read the cache before
 256         * calling us.
 257         */
 258        if (!active_cache)
 259                return 0;
 260
 261        len = strlen(name);
 262        pos = cache_name_pos(name, len);
 263        if (pos < 0)
 264                return 0;
 265        ce = active_cache[pos];
 266        if ((lstat(name, &st) < 0) ||
 267            !S_ISREG(st.st_mode) || /* careful! */
 268            ce_match_stat(ce, &st) ||
 269            memcmp(sha1, ce->sha1, 20))
 270                return 0;
 271        /* we return 1 only when we can stat, it is a regular file,
 272         * stat information matches, and sha1 recorded in the cache
 273         * matches.  I.e. we know the file in the work tree really is
 274         * the same as the <name, sha1> pair.
 275         */
 276        return 1;
 277}
 278
 279static struct sha1_size_cache {
 280        unsigned char sha1[20];
 281        unsigned long size;
 282} **sha1_size_cache;
 283static int sha1_size_cache_nr, sha1_size_cache_alloc;
 284
 285static struct sha1_size_cache *locate_size_cache(unsigned char *sha1,
 286                                                 int find_only,
 287                                                 unsigned long size)
 288{
 289        int first, last;
 290        struct sha1_size_cache *e;
 291
 292        first = 0;
 293        last = sha1_size_cache_nr;
 294        while (last > first) {
 295                int cmp, next = (last + first) >> 1;
 296                e = sha1_size_cache[next];
 297                cmp = memcmp(e->sha1, sha1, 20);
 298                if (!cmp)
 299                        return e;
 300                if (cmp < 0) {
 301                        last = next;
 302                        continue;
 303                }
 304                first = next+1;
 305        }
 306        /* not found */
 307        if (find_only)
 308                return NULL;
 309        /* insert to make it at "first" */
 310        if (sha1_size_cache_alloc <= sha1_size_cache_nr) {
 311                sha1_size_cache_alloc = alloc_nr(sha1_size_cache_alloc);
 312                sha1_size_cache = xrealloc(sha1_size_cache,
 313                                           sha1_size_cache_alloc *
 314                                           sizeof(*sha1_size_cache));
 315        }
 316        sha1_size_cache_nr++;
 317        if (first < sha1_size_cache_nr)
 318                memmove(sha1_size_cache + first + 1, sha1_size_cache + first,
 319                        (sha1_size_cache_nr - first - 1) *
 320                        sizeof(*sha1_size_cache));
 321        e = xmalloc(sizeof(struct sha1_size_cache));
 322        sha1_size_cache[first] = e;
 323        memcpy(e->sha1, sha1, 20);
 324        e->size = size;
 325        return e;
 326}
 327
 328/*
 329 * While doing rename detection and pickaxe operation, we may need to
 330 * grab the data for the blob (or file) for our own in-core comparison.
 331 * diff_filespec has data and size fields for this purpose.
 332 */
 333int diff_populate_filespec(struct diff_filespec *s, int size_only)
 334{
 335        int err = 0;
 336        if (!DIFF_FILE_VALID(s))
 337                die("internal error: asking to populate invalid file.");
 338        if (S_ISDIR(s->mode))
 339                return -1;
 340
 341        if (!use_size_cache)
 342                size_only = 0;
 343
 344        if (s->data)
 345                return err;
 346        if (!s->sha1_valid ||
 347            work_tree_matches(s->path, s->sha1)) {
 348                struct stat st;
 349                int fd;
 350                if (lstat(s->path, &st) < 0) {
 351                        if (errno == ENOENT) {
 352                        err_empty:
 353                                err = -1;
 354                        empty:
 355                                s->data = "";
 356                                s->size = 0;
 357                                return err;
 358                        }
 359                }
 360                s->size = st.st_size;
 361                if (!s->size)
 362                        goto empty;
 363                if (size_only)
 364                        return 0;
 365                if (S_ISLNK(st.st_mode)) {
 366                        int ret;
 367                        s->data = xmalloc(s->size);
 368                        s->should_free = 1;
 369                        ret = readlink(s->path, s->data, s->size);
 370                        if (ret < 0) {
 371                                free(s->data);
 372                                goto err_empty;
 373                        }
 374                        return 0;
 375                }
 376                fd = open(s->path, O_RDONLY);
 377                if (fd < 0)
 378                        goto err_empty;
 379                s->data = mmap(NULL, s->size, PROT_READ, MAP_PRIVATE, fd, 0);
 380                close(fd);
 381                if (s->data == MAP_FAILED)
 382                        goto err_empty;
 383                s->should_munmap = 1;
 384        }
 385        else {
 386                char type[20];
 387                struct sha1_size_cache *e;
 388
 389                if (size_only) {
 390                        e = locate_size_cache(s->sha1, 1, 0);
 391                        if (e) {
 392                                s->size = e->size;
 393                                return 0;
 394                        }
 395                        if (!sha1_object_info(s->sha1, type, &s->size))
 396                                locate_size_cache(s->sha1, 0, s->size);
 397                }
 398                else {
 399                        s->data = read_sha1_file(s->sha1, type, &s->size);
 400                        s->should_free = 1;
 401                }
 402        }
 403        return 0;
 404}
 405
 406void diff_free_filespec_data(struct diff_filespec *s)
 407{
 408        if (s->should_free)
 409                free(s->data);
 410        else if (s->should_munmap)
 411                munmap(s->data, s->size);
 412        s->should_free = s->should_munmap = 0;
 413        s->data = NULL;
 414}
 415
 416static void prep_temp_blob(struct diff_tempfile *temp,
 417                           void *blob,
 418                           unsigned long size,
 419                           unsigned char *sha1,
 420                           int mode)
 421{
 422        int fd;
 423
 424        strcpy(temp->tmp_path, ".diff_XXXXXX");
 425        fd = mkstemp(temp->tmp_path);
 426        if (fd < 0)
 427                die("unable to create temp-file");
 428        if (write(fd, blob, size) != size)
 429                die("unable to write temp-file");
 430        close(fd);
 431        temp->name = temp->tmp_path;
 432        strcpy(temp->hex, sha1_to_hex(sha1));
 433        temp->hex[40] = 0;
 434        sprintf(temp->mode, "%06o", mode);
 435}
 436
 437static void prepare_temp_file(const char *name,
 438                              struct diff_tempfile *temp,
 439                              struct diff_filespec *one)
 440{
 441        if (!DIFF_FILE_VALID(one)) {
 442        not_a_valid_file:
 443                /* A '-' entry produces this for file-2, and
 444                 * a '+' entry produces this for file-1.
 445                 */
 446                temp->name = "/dev/null";
 447                strcpy(temp->hex, ".");
 448                strcpy(temp->mode, ".");
 449                return;
 450        }
 451
 452        if (!one->sha1_valid ||
 453            work_tree_matches(name, one->sha1)) {
 454                struct stat st;
 455                if (lstat(name, &st) < 0) {
 456                        if (errno == ENOENT)
 457                                goto not_a_valid_file;
 458                        die("stat(%s): %s", name, strerror(errno));
 459                }
 460                if (S_ISLNK(st.st_mode)) {
 461                        int ret;
 462                        char *buf, buf_[1024];
 463                        buf = ((sizeof(buf_) < st.st_size) ?
 464                               xmalloc(st.st_size) : buf_);
 465                        ret = readlink(name, buf, st.st_size);
 466                        if (ret < 0)
 467                                die("readlink(%s)", name);
 468                        prep_temp_blob(temp, buf, st.st_size,
 469                                       (one->sha1_valid ?
 470                                        one->sha1 : null_sha1),
 471                                       (one->sha1_valid ?
 472                                        one->mode : S_IFLNK));
 473                }
 474                else {
 475                        /* we can borrow from the file in the work tree */
 476                        temp->name = name;
 477                        if (!one->sha1_valid)
 478                                strcpy(temp->hex, sha1_to_hex(null_sha1));
 479                        else
 480                                strcpy(temp->hex, sha1_to_hex(one->sha1));
 481                        /* Even though we may sometimes borrow the
 482                         * contents from the work tree, we always want
 483                         * one->mode.  mode is trustworthy even when
 484                         * !(one->sha1_valid), as long as
 485                         * DIFF_FILE_VALID(one).
 486                         */
 487                        sprintf(temp->mode, "%06o", one->mode);
 488                }
 489                return;
 490        }
 491        else {
 492                if (diff_populate_filespec(one, 0))
 493                        die("cannot read data blob for %s", one->path);
 494                prep_temp_blob(temp, one->data, one->size,
 495                               one->sha1, one->mode);
 496        }
 497}
 498
 499static void remove_tempfile(void)
 500{
 501        int i;
 502
 503        for (i = 0; i < 2; i++)
 504                if (diff_temp[i].name == diff_temp[i].tmp_path) {
 505                        unlink(diff_temp[i].name);
 506                        diff_temp[i].name = NULL;
 507                }
 508}
 509
 510static void remove_tempfile_on_signal(int signo)
 511{
 512        remove_tempfile();
 513}
 514
 515/* An external diff command takes:
 516 *
 517 * diff-cmd name infile1 infile1-sha1 infile1-mode \
 518 *               infile2 infile2-sha1 infile2-mode [ rename-to ]
 519 *
 520 */
 521static void run_external_diff(const char *pgm,
 522                              const char *name,
 523                              const char *other,
 524                              struct diff_filespec *one,
 525                              struct diff_filespec *two,
 526                              const char *xfrm_msg,
 527                              int complete_rewrite)
 528{
 529        struct diff_tempfile *temp = diff_temp;
 530        pid_t pid;
 531        int status;
 532        static int atexit_asked = 0;
 533
 534        if (one && two) {
 535                prepare_temp_file(name, &temp[0], one);
 536                prepare_temp_file(other ? : name, &temp[1], two);
 537                if (! atexit_asked &&
 538                    (temp[0].name == temp[0].tmp_path ||
 539                     temp[1].name == temp[1].tmp_path)) {
 540                        atexit_asked = 1;
 541                        atexit(remove_tempfile);
 542                }
 543                signal(SIGINT, remove_tempfile_on_signal);
 544        }
 545
 546        fflush(NULL);
 547        pid = fork();
 548        if (pid < 0)
 549                die("unable to fork");
 550        if (!pid) {
 551                if (pgm) {
 552                        if (one && two) {
 553                                const char *exec_arg[10];
 554                                const char **arg = &exec_arg[0];
 555                                *arg++ = pgm;
 556                                *arg++ = name;
 557                                *arg++ = temp[0].name;
 558                                *arg++ = temp[0].hex;
 559                                *arg++ = temp[0].mode;
 560                                *arg++ = temp[1].name;
 561                                *arg++ = temp[1].hex;
 562                                *arg++ = temp[1].mode;
 563                                if (other) {
 564                                        *arg++ = other;
 565                                        *arg++ = xfrm_msg;
 566                                }
 567                                *arg = NULL;
 568                                execvp(pgm, (char *const*) exec_arg);
 569                        }
 570                        else
 571                                execlp(pgm, pgm, name, NULL);
 572                }
 573                /*
 574                 * otherwise we use the built-in one.
 575                 */
 576                if (one && two)
 577                        builtin_diff(name, other ? : name, temp, xfrm_msg,
 578                                     complete_rewrite);
 579                else
 580                        printf("* Unmerged path %s\n", name);
 581                exit(0);
 582        }
 583        if (waitpid(pid, &status, 0) < 0 ||
 584            !WIFEXITED(status) || WEXITSTATUS(status)) {
 585                /* Earlier we did not check the exit status because
 586                 * diff exits non-zero if files are different, and
 587                 * we are not interested in knowing that.  It was a
 588                 * mistake which made it harder to quit a diff-*
 589                 * session that uses the git-apply-patch-script as
 590                 * the GIT_EXTERNAL_DIFF.  A custom GIT_EXTERNAL_DIFF
 591                 * should also exit non-zero only when it wants to
 592                 * abort the entire diff-* session.
 593                 */
 594                remove_tempfile();
 595                fprintf(stderr, "external diff died, stopping at %s.\n", name);
 596                exit(1);
 597        }
 598        remove_tempfile();
 599}
 600
 601static void run_diff(struct diff_filepair *p)
 602{
 603        const char *pgm = external_diff();
 604        char msg_[PATH_MAX*2+200], *xfrm_msg;
 605        struct diff_filespec *one;
 606        struct diff_filespec *two;
 607        const char *name;
 608        const char *other;
 609        int complete_rewrite = 0;
 610
 611        if (DIFF_PAIR_UNMERGED(p)) {
 612                /* unmerged */
 613                run_external_diff(pgm, p->one->path, NULL, NULL, NULL, NULL,
 614                                  0);
 615                return;
 616        }
 617
 618        name = p->one->path;
 619        other = (strcmp(name, p->two->path) ? p->two->path : NULL);
 620        one = p->one; two = p->two;
 621        switch (p->status) {
 622        case DIFF_STATUS_COPIED:
 623                sprintf(msg_,
 624                        "similarity index %d%%\n"
 625                        "copy from %s\n"
 626                        "copy to %s",
 627                        (int)(0.5 + p->score * 100.0/MAX_SCORE),
 628                        name, other);
 629                xfrm_msg = msg_;
 630                break;
 631        case DIFF_STATUS_RENAMED:
 632                sprintf(msg_,
 633                        "similarity index %d%%\n"
 634                        "rename from %s\n"
 635                        "rename to %s",
 636                        (int)(0.5 + p->score * 100.0/MAX_SCORE),
 637                        name, other);
 638                xfrm_msg = msg_;
 639                break;
 640        case DIFF_STATUS_MODIFIED:
 641                if (p->score) {
 642                        sprintf(msg_,
 643                                "dissimilarity index %d%%",
 644                                (int)(0.5 + p->score * 100.0/MAX_SCORE));
 645                        xfrm_msg = msg_;
 646                        complete_rewrite = 1;
 647                        break;
 648                }
 649                /* fallthru */
 650        default:
 651                xfrm_msg = NULL;
 652        }
 653
 654        if (!pgm &&
 655            DIFF_FILE_VALID(one) && DIFF_FILE_VALID(two) &&
 656            (S_IFMT & one->mode) != (S_IFMT & two->mode)) {
 657                /* a filepair that changes between file and symlink
 658                 * needs to be split into deletion and creation.
 659                 */
 660                struct diff_filespec *null = alloc_filespec(two->path);
 661                run_external_diff(NULL, name, other, one, null, xfrm_msg, 0);
 662                free(null);
 663                null = alloc_filespec(one->path);
 664                run_external_diff(NULL, name, other, null, two, xfrm_msg, 0);
 665                free(null);
 666        }
 667        else
 668                run_external_diff(pgm, name, other, one, two, xfrm_msg,
 669                                  complete_rewrite);
 670}
 671
 672void diff_setup(int flags)
 673{
 674        if (flags & DIFF_SETUP_REVERSE)
 675                reverse_diff = 1;
 676        if (flags & DIFF_SETUP_USE_CACHE) {
 677                if (!active_cache)
 678                        /* read-cache does not die even when it fails
 679                         * so it is safe for us to do this here.  Also
 680                         * it does not smudge active_cache or active_nr
 681                         * when it fails, so we do not have to worry about
 682                         * cleaning it up oufselves either.
 683                         */
 684                        read_cache();
 685        }
 686        if (flags & DIFF_SETUP_USE_SIZE_CACHE)
 687                use_size_cache = 1;
 688        
 689}
 690
 691static int parse_num(const char **cp_p)
 692{
 693        int num, scale, ch, cnt;
 694        const char *cp = *cp_p;
 695
 696        cnt = num = 0;
 697        scale = 1;
 698        while ('0' <= (ch = *cp) && ch <= '9') {
 699                if (cnt++ < 5) {
 700                        /* We simply ignore more than 5 digits precision. */
 701                        scale *= 10;
 702                        num = num * 10 + ch - '0';
 703                }
 704                *cp++;
 705        }
 706        *cp_p = cp;
 707
 708        /* user says num divided by scale and we say internally that
 709         * is MAX_SCORE * num / scale.
 710         */
 711        return (MAX_SCORE * num / scale);
 712}
 713
 714int diff_scoreopt_parse(const char *opt)
 715{
 716        int opt1, opt2, cmd;
 717
 718        if (*opt++ != '-')
 719                return -1;
 720        cmd = *opt++;
 721        if (cmd != 'M' && cmd != 'C' && cmd != 'B')
 722                return -1; /* that is not a -M, -C nor -B option */
 723
 724        opt1 = parse_num(&opt);
 725        if (cmd != 'B')
 726                opt2 = 0;
 727        else {
 728                if (*opt == 0)
 729                        opt2 = 0;
 730                else if (*opt != '/')
 731                        return -1; /* we expect -B80/99 or -B80 */
 732                else {
 733                        opt++;
 734                        opt2 = parse_num(&opt);
 735                }
 736        }
 737        if (*opt != 0)
 738                return -1;
 739        return opt1 | (opt2 << 16);
 740}
 741
 742struct diff_queue_struct diff_queued_diff;
 743
 744void diff_q(struct diff_queue_struct *queue, struct diff_filepair *dp)
 745{
 746        if (queue->alloc <= queue->nr) {
 747                queue->alloc = alloc_nr(queue->alloc);
 748                queue->queue = xrealloc(queue->queue,
 749                                        sizeof(dp) * queue->alloc);
 750        }
 751        queue->queue[queue->nr++] = dp;
 752}
 753
 754struct diff_filepair *diff_queue(struct diff_queue_struct *queue,
 755                                 struct diff_filespec *one,
 756                                 struct diff_filespec *two)
 757{
 758        struct diff_filepair *dp = xmalloc(sizeof(*dp));
 759        dp->one = one;
 760        dp->two = two;
 761        dp->score = 0;
 762        dp->status = 0;
 763        dp->source_stays = 0;
 764        dp->broken_pair = 0;
 765        diff_q(queue, dp);
 766        return dp;
 767}
 768
 769void diff_free_filepair(struct diff_filepair *p)
 770{
 771        diff_free_filespec_data(p->one);
 772        diff_free_filespec_data(p->two);
 773        free(p);
 774}
 775
 776static void diff_flush_raw(struct diff_filepair *p,
 777                           int line_termination,
 778                           int inter_name_termination)
 779{
 780        int two_paths;
 781        char status[10];
 782
 783        if (line_termination) {
 784                const char *err = "path %s cannot be expressed without -z";
 785                if (strchr(p->one->path, line_termination) ||
 786                    strchr(p->one->path, inter_name_termination))
 787                        die(err, p->one->path);
 788                if (strchr(p->two->path, line_termination) ||
 789                    strchr(p->two->path, inter_name_termination))
 790                        die(err, p->two->path);
 791        }
 792
 793        if (p->score)
 794                sprintf(status, "%c%03d", p->status,
 795                        (int)(0.5 + p->score * 100.0/MAX_SCORE));
 796        else {
 797                status[0] = p->status;
 798                status[1] = 0;
 799        }
 800        switch (p->status) {
 801        case DIFF_STATUS_COPIED:
 802        case DIFF_STATUS_RENAMED:
 803                two_paths = 1;
 804                break;
 805        case DIFF_STATUS_ADDED:
 806        case DIFF_STATUS_DELETED:
 807                two_paths = 0;
 808                break;
 809        default:
 810                two_paths = 0;
 811                break;
 812        }
 813        printf(":%06o %06o %s ",
 814               p->one->mode, p->two->mode, sha1_to_hex(p->one->sha1));
 815        printf("%s %s%c%s",
 816               sha1_to_hex(p->two->sha1),
 817               status,
 818               inter_name_termination,
 819               p->one->path);
 820        if (two_paths)
 821                printf("%c%s", inter_name_termination, p->two->path);
 822        putchar(line_termination);
 823}
 824
 825static void diff_flush_name(struct diff_filepair *p,
 826                            int line_termination)
 827{
 828        printf("%s%c", p->two->path, line_termination);
 829}
 830
 831int diff_unmodified_pair(struct diff_filepair *p)
 832{
 833        /* This function is written stricter than necessary to support
 834         * the currently implemented transformers, but the idea is to
 835         * let transformers to produce diff_filepairs any way they want,
 836         * and filter and clean them up here before producing the output.
 837         */
 838        struct diff_filespec *one, *two;
 839
 840        if (DIFF_PAIR_UNMERGED(p))
 841                return 0; /* unmerged is interesting */
 842
 843        one = p->one;
 844        two = p->two;
 845
 846        /* deletion, addition, mode or type change
 847         * and rename are all interesting.
 848         */
 849        if (DIFF_FILE_VALID(one) != DIFF_FILE_VALID(two) ||
 850            DIFF_PAIR_MODE_CHANGED(p) ||
 851            strcmp(one->path, two->path))
 852                return 0;
 853
 854        /* both are valid and point at the same path.  that is, we are
 855         * dealing with a change.
 856         */
 857        if (one->sha1_valid && two->sha1_valid &&
 858            !memcmp(one->sha1, two->sha1, sizeof(one->sha1)))
 859                return 1; /* no change */
 860        if (!one->sha1_valid && !two->sha1_valid)
 861                return 1; /* both look at the same file on the filesystem. */
 862        return 0;
 863}
 864
 865static void diff_flush_patch(struct diff_filepair *p)
 866{
 867        if (diff_unmodified_pair(p))
 868                return;
 869
 870        if ((DIFF_FILE_VALID(p->one) && S_ISDIR(p->one->mode)) ||
 871            (DIFF_FILE_VALID(p->two) && S_ISDIR(p->two->mode)))
 872                return; /* no tree diffs in patch format */ 
 873
 874        run_diff(p);
 875}
 876
 877int diff_queue_is_empty(void)
 878{
 879        struct diff_queue_struct *q = &diff_queued_diff;
 880        int i;
 881        for (i = 0; i < q->nr; i++)
 882                if (!diff_unmodified_pair(q->queue[i]))
 883                        return 0;
 884        return 1;
 885}
 886
 887#if DIFF_DEBUG
 888void diff_debug_filespec(struct diff_filespec *s, int x, const char *one)
 889{
 890        fprintf(stderr, "queue[%d] %s (%s) %s %06o %s\n",
 891                x, one ? : "",
 892                s->path,
 893                DIFF_FILE_VALID(s) ? "valid" : "invalid",
 894                s->mode,
 895                s->sha1_valid ? sha1_to_hex(s->sha1) : "");
 896        fprintf(stderr, "queue[%d] %s size %lu flags %d\n",
 897                x, one ? : "",
 898                s->size, s->xfrm_flags);
 899}
 900
 901void diff_debug_filepair(const struct diff_filepair *p, int i)
 902{
 903        diff_debug_filespec(p->one, i, "one");
 904        diff_debug_filespec(p->two, i, "two");
 905        fprintf(stderr, "score %d, status %c stays %d broken %d\n",
 906                p->score, p->status ? : '?',
 907                p->source_stays, p->broken_pair);
 908}
 909
 910void diff_debug_queue(const char *msg, struct diff_queue_struct *q)
 911{
 912        int i;
 913        if (msg)
 914                fprintf(stderr, "%s\n", msg);
 915        fprintf(stderr, "q->nr = %d\n", q->nr);
 916        for (i = 0; i < q->nr; i++) {
 917                struct diff_filepair *p = q->queue[i];
 918                diff_debug_filepair(p, i);
 919        }
 920}
 921#endif
 922
 923static void diff_resolve_rename_copy(void)
 924{
 925        int i, j;
 926        struct diff_filepair *p, *pp;
 927        struct diff_queue_struct *q = &diff_queued_diff;
 928
 929        diff_debug_queue("resolve-rename-copy", q);
 930
 931        for (i = 0; i < q->nr; i++) {
 932                p = q->queue[i];
 933                p->status = 0; /* undecided */
 934                if (DIFF_PAIR_UNMERGED(p))
 935                        p->status = DIFF_STATUS_UNMERGED;
 936                else if (!DIFF_FILE_VALID(p->one))
 937                        p->status = DIFF_STATUS_ADDED;
 938                else if (!DIFF_FILE_VALID(p->two))
 939                        p->status = DIFF_STATUS_DELETED;
 940                else if (DIFF_PAIR_TYPE_CHANGED(p))
 941                        p->status = DIFF_STATUS_TYPE_CHANGED;
 942
 943                /* from this point on, we are dealing with a pair
 944                 * whose both sides are valid and of the same type, i.e.
 945                 * either in-place edit or rename/copy edit.
 946                 */
 947                else if (DIFF_PAIR_RENAME(p)) {
 948                        if (p->source_stays) {
 949                                p->status = DIFF_STATUS_COPIED;
 950                                continue;
 951                        }
 952                        /* See if there is some other filepair that
 953                         * copies from the same source as us.  If so
 954                         * we are a copy.  Otherwise we are a rename.
 955                         */
 956                        for (j = i + 1; j < q->nr; j++) {
 957                                pp = q->queue[j];
 958                                if (strcmp(pp->one->path, p->one->path))
 959                                        continue; /* not us */
 960                                if (!DIFF_PAIR_RENAME(pp))
 961                                        continue; /* not a rename/copy */
 962                                /* pp is a rename/copy from the same source */
 963                                p->status = DIFF_STATUS_COPIED;
 964                                break;
 965                        }
 966                        if (!p->status)
 967                                p->status = DIFF_STATUS_RENAMED;
 968                }
 969                else if (memcmp(p->one->sha1, p->two->sha1, 20) ||
 970                         p->one->mode != p->two->mode)
 971                        p->status = DIFF_STATUS_MODIFIED;
 972                else {
 973                        /* This is a "no-change" entry and should not
 974                         * happen anymore, but prepare for broken callers.
 975                         */
 976                        error("feeding unmodified %s to diffcore",
 977                              p->one->path);
 978                        p->status = DIFF_STATUS_UNKNOWN;
 979                }
 980        }
 981        diff_debug_queue("resolve-rename-copy done", q);
 982}
 983
 984void diff_flush(int diff_output_style, int line_termination)
 985{
 986        struct diff_queue_struct *q = &diff_queued_diff;
 987        int i;
 988        int inter_name_termination = '\t';
 989
 990        if (!line_termination)
 991                inter_name_termination = 0;
 992
 993        for (i = 0; i < q->nr; i++) {
 994                struct diff_filepair *p = q->queue[i];
 995                if ((diff_output_style == DIFF_FORMAT_NO_OUTPUT) ||
 996                    (p->status == DIFF_STATUS_UNKNOWN))
 997                        continue;
 998                if (p->status == 0)
 999                        die("internal error in diff-resolve-rename-copy");
1000                switch (diff_output_style) {
1001                case DIFF_FORMAT_PATCH:
1002                        diff_flush_patch(p);
1003                        break;
1004                case DIFF_FORMAT_RAW:
1005                        diff_flush_raw(p, line_termination,
1006                                       inter_name_termination);
1007                        break;
1008                case DIFF_FORMAT_NAME:
1009                        diff_flush_name(p, line_termination);
1010                        break;
1011                }
1012        }
1013        for (i = 0; i < q->nr; i++)
1014                diff_free_filepair(q->queue[i]);
1015        free(q->queue);
1016        q->queue = NULL;
1017        q->nr = q->alloc = 0;
1018}
1019
1020static void diffcore_apply_filter(const char *filter)
1021{
1022        int i;
1023        struct diff_queue_struct *q = &diff_queued_diff;
1024        struct diff_queue_struct outq;
1025        outq.queue = NULL;
1026        outq.nr = outq.alloc = 0;
1027
1028        if (!filter)
1029                return;
1030
1031        if (strchr(filter, DIFF_STATUS_FILTER_AON)) {
1032                int found;
1033                for (i = found = 0; !found && i < q->nr; i++) {
1034                        struct diff_filepair *p = q->queue[i];
1035                        if (((p->status == DIFF_STATUS_MODIFIED) &&
1036                             ((p->score &&
1037                               strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
1038                              (!p->score &&
1039                               strchr(filter, DIFF_STATUS_MODIFIED)))) ||
1040                            ((p->status != DIFF_STATUS_MODIFIED) &&
1041                             strchr(filter, p->status)))
1042                                found++;
1043                }
1044                if (found)
1045                        return;
1046
1047                /* otherwise we will clear the whole queue
1048                 * by copying the empty outq at the end of this
1049                 * function, but first clear the current entries
1050                 * in the queue.
1051                 */
1052                for (i = 0; i < q->nr; i++)
1053                        diff_free_filepair(q->queue[i]);
1054        }
1055        else {
1056                /* Only the matching ones */
1057                for (i = 0; i < q->nr; i++) {
1058                        struct diff_filepair *p = q->queue[i];
1059
1060                        if (((p->status == DIFF_STATUS_MODIFIED) &&
1061                             ((p->score &&
1062                               strchr(filter, DIFF_STATUS_FILTER_BROKEN)) ||
1063                              (!p->score &&
1064                               strchr(filter, DIFF_STATUS_MODIFIED)))) ||
1065                            ((p->status != DIFF_STATUS_MODIFIED) &&
1066                             strchr(filter, p->status)))
1067                                diff_q(&outq, p);
1068                        else
1069                                diff_free_filepair(p);
1070                }
1071        }
1072        free(q->queue);
1073        *q = outq;
1074}
1075
1076void diffcore_std(const char **paths,
1077                  int detect_rename, int rename_score,
1078                  const char *pickaxe, int pickaxe_opts,
1079                  int break_opt,
1080                  const char *orderfile,
1081                  const char *filter)
1082{
1083        if (paths && paths[0])
1084                diffcore_pathspec(paths);
1085        if (break_opt != -1)
1086                diffcore_break(break_opt);
1087        if (detect_rename)
1088                diffcore_rename(detect_rename, rename_score);
1089        if (break_opt != -1)
1090                diffcore_merge_broken();
1091        if (pickaxe)
1092                diffcore_pickaxe(pickaxe, pickaxe_opts);
1093        if (orderfile)
1094                diffcore_order(orderfile);
1095        diff_resolve_rename_copy();
1096        diffcore_apply_filter(filter);
1097}
1098
1099
1100void diffcore_std_no_resolve(const char **paths,
1101                             const char *pickaxe, int pickaxe_opts,
1102                             const char *orderfile,
1103                             const char *filter)
1104{
1105        if (paths && paths[0])
1106                diffcore_pathspec(paths);
1107        if (pickaxe)
1108                diffcore_pickaxe(pickaxe, pickaxe_opts);
1109        if (orderfile)
1110                diffcore_order(orderfile);
1111        diffcore_apply_filter(filter);
1112}
1113
1114void diff_addremove(int addremove, unsigned mode,
1115                    const unsigned char *sha1,
1116                    const char *base, const char *path)
1117{
1118        char concatpath[PATH_MAX];
1119        struct diff_filespec *one, *two;
1120
1121        /* This may look odd, but it is a preparation for
1122         * feeding "there are unchanged files which should
1123         * not produce diffs, but when you are doing copy
1124         * detection you would need them, so here they are"
1125         * entries to the diff-core.  They will be prefixed
1126         * with something like '=' or '*' (I haven't decided
1127         * which but should not make any difference).
1128         * Feeding the same new and old to diff_change() 
1129         * also has the same effect.
1130         * Before the final output happens, they are pruned after
1131         * merged into rename/copy pairs as appropriate.
1132         */
1133        if (reverse_diff)
1134                addremove = (addremove == '+' ? '-' :
1135                             addremove == '-' ? '+' : addremove);
1136
1137        if (!path) path = "";
1138        sprintf(concatpath, "%s%s", base, path);
1139        one = alloc_filespec(concatpath);
1140        two = alloc_filespec(concatpath);
1141
1142        if (addremove != '+')
1143                fill_filespec(one, sha1, mode);
1144        if (addremove != '-')
1145                fill_filespec(two, sha1, mode);
1146
1147        diff_queue(&diff_queued_diff, one, two);
1148}
1149
1150void diff_helper_input(unsigned old_mode,
1151                       unsigned new_mode,
1152                       const unsigned char *old_sha1,
1153                       const unsigned char *new_sha1,
1154                       const char *old_path,
1155                       int status,
1156                       int score,
1157                       const char *new_path)
1158{
1159        struct diff_filespec *one, *two;
1160        struct diff_filepair *dp;
1161
1162        one = alloc_filespec(old_path);
1163        two = alloc_filespec(new_path);
1164        if (old_mode)
1165                fill_filespec(one, old_sha1, old_mode);
1166        if (new_mode)
1167                fill_filespec(two, new_sha1, new_mode);
1168        dp = diff_queue(&diff_queued_diff, one, two);
1169        dp->score = score * MAX_SCORE / 100;
1170        dp->status = status;
1171}
1172
1173void diff_change(unsigned old_mode, unsigned new_mode,
1174                 const unsigned char *old_sha1,
1175                 const unsigned char *new_sha1,
1176                 const char *base, const char *path) 
1177{
1178        char concatpath[PATH_MAX];
1179        struct diff_filespec *one, *two;
1180
1181        if (reverse_diff) {
1182                unsigned tmp;
1183                const unsigned char *tmp_c;
1184                tmp = old_mode; old_mode = new_mode; new_mode = tmp;
1185                tmp_c = old_sha1; old_sha1 = new_sha1; new_sha1 = tmp_c;
1186        }
1187        if (!path) path = "";
1188        sprintf(concatpath, "%s%s", base, path);
1189        one = alloc_filespec(concatpath);
1190        two = alloc_filespec(concatpath);
1191        fill_filespec(one, old_sha1, old_mode);
1192        fill_filespec(two, new_sha1, new_mode);
1193
1194        diff_queue(&diff_queued_diff, one, two);
1195}
1196
1197void diff_unmerge(const char *path)
1198{
1199        struct diff_filespec *one, *two;
1200        one = alloc_filespec(path);
1201        two = alloc_filespec(path);
1202        diff_queue(&diff_queued_diff, one, two);
1203}